var alpha = ['a', 'b', 'c'];
var num = [1, 2, 3];

console.log(alpha.concat(num)); // [ "a", "b", "c", 1, 2, 3 ]

var num1 = [1, 2, 3], num2 = [4, 5, 6], num3 = [7, 8, 9];
var nums = num1.concat(num2, num3);
console.log(nums); // [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
console.log(num1); // [ 1, 2, 3 ]

var age = [10, 11, 12];
var ageArr = age.concat(20, [21, 22]);
console.log(ageArr); // [ 10, 11, 12, 20, 21, 22 ]

